Computer systems generally include a mass storage component, like a hard disk drive (HDD), for example, to store the operational and application software of one or more host processing units. IBM's AT bus has become a defacto standard for linking the host processing unit with the HDD and for providing the protocol for communication therebetween. AT is a trademark of the IBM Corporation. Specifications for such linking and communication over the AT bus are currently provided by the ANSI standard published as NCITS 397-2005 AT Attachment-7 and AT Attachment-7 With Packet Interface (ATA/ATAPI-7), Vol. 1,which is incorporated herein by reference in its entirety. These specifications may be located over the world wide web at the website “www.incits.org”. A security mode feature is included in the AT bus protocol standard, substantially in Section 4.7 thereof, which is intended to prevent unintended user access or unintended software, like a rogue or virus software, for example, which may have penetrated the host computer's defenses, from locking out the user from accessing software from the HDD.
Section 4.7 of the ATA/ATAPI-7 specification sets forth a password system for restricting access to user software stored on the HDD. In this standard, various predetermined commands issued by the host processing unit or elements thereof permit setting a password and accessing the drive storage with the password. However, the standard has certain drawbacks, which will be described in greater detail below, which may permit the password to be scrambled or changed, under certain conditions, by unintended software, thus locking out the USER from accessing the mass storage component.